This invention generally relates to reclosable flexible bags whose interior volume is hermetically sealed when the bag is closed. In particular, the invention relates to, but is not limited to, evacuable reclosable storage bags having a zipper that is closed (but not opened) by operation of a slider or clip mounted on the zipper.
Collapsible, evacuable storage containers typically include a flexible, airtight bag, an opening through which a compressible article is inserted inside the bag, a zipper for closing the opening and hermetically sealing the bag, a U-shaped slider for closing the zipper, and one or more one-way valves or vents through which excess air is evacuated from the bag. A user places an article into the bag through the opening, seals the opening, and then removes air from the bag through the one-way valve or valves. As air is removed, the compressible article contained therein may be significantly compressed so that it is easier to transport and requires substantially less storage space.
Collapsible, evacuable storage containers are beneficial for reasons in addition to those associated with compression of the stored article. For example, removal of the air from the storage container inhibits the growth of destructive organisms, such as moths, silverfish, and bacteria, which require oxygen to survive and propagate. Moreover, such containers, being impervious to moisture, inhibit the growth of mildew.
Not only large, compressible items such as clothing may be stored in a collapsible, evacuable storage container. For example, it may be desirable to store bulk items made of small particles, such as powders or granulated resins, in an evacuated container. One situation that commonly occurs is that a particular bulk item is shipped in a large, rigid container such as a drum. Bulk items may be moisture sensitive and are sealed against moisture during shipment. But many times a user does not need to use the entire contents of the large container, and so once exposed to air the remaining bulk contents quickly become unusable and are thus wasted.
Many commercially available evacuable storage bags are provided with an inverted U-shaped slider or clip mounted to the plastic zipper. This slider is capable of closing an open zipper, i.e., by camming the opposing zipper strips into engagement during slider travel in either direction, but cannot be used to open a closed zipper. The slider does not have means for opening the zipper because typically such means would leave a gap in the zipper, thereby preventing formation of a hermetic seal.
In known reclosable bags, the zipper comprises a pair of mutually interlockable zipper strips, each zipper strip having one or more generally constant profiles extending across the mouth of the bag. For example, it is known to provide a reclosable bag having dual zippers which extend in parallel across the mouth of the bag. The ends of the zipper strips are joined together at the sides of the bag. For example, it is known to fuse the ends of the zipper strips together, at the same time that the bag side seals are formed, by the application of heat and pressure. This “thermal crushing” of the plastic zipper creates a transition between “as is” zipper and crushed zipper that is susceptible to the presence of leaks through which air can enter an evacuated bag. In addition, such crushing leaves the surface material flat at either end where the zipper ends are joined to each other and to the webs of film that form the front and rear walls of the bag.
There is a continuing need for improvements in the construction of flexible storage containers that need to be hermetically sealed. In particular, there is a need for an improved evacuable storage container wherein leakage is eliminated in the areas where the bag side seals overlap the joined ends of the zipper strips. There is also a need for a leakproof construction that provides means for stopping a U-shaped slider at either end of the bag mouth as it travels along the closure.